To make tart shell, put flour, butter and parmigiano reggiano in the bowl of a food processor and process until mixture resembles breadcrumbs. Add egg yolk and water, then process until mixture begins to form a ball. (Add a little extra water if necessary.)
Preheat oven to 200°C. Turn dough onto a lightly floured surface and knead until just smooth. Roll out on a floured surface until 32cm in diameter. Line a 28cm x 2.5cm quiche tin (with removable base) with dough. Trim edges. Freeze for 15 minutes.
Transfer tart shell to a large oven tray. Line tart shell with a sheet of baking paper and fill with uncooked rice or baking beans. Bake for 15 minutes, remove paper and rice or beans. Reduce temperature to 180°C and bake for a further 10 minutes or until lightly golden on edges. Cool slightly.
To make filling, put ricotta, cheddar, egg, thyme leaves and ½ teaspoon of the salt in a bowl. Season with pepper. Beat using a handheld electric beater until just combined. Break goats cheese into large pieces over ricotta mixture and beat for another 10 seconds or until just combined.
Spread mixture evenly over tart shell. Trim ends of green and white zucchini, then using a mandolin, thinly slice into rounds. Overlap slices close together on top of cheese mixture, starting from outer edge. Alternate with a circle of green zucchini, then white. Spray with olive oil and sprinkle with remaining salt.
Bake for 40-45 minutes or until zucchini begins to colour, turning quiche tin halfway through. Allow to cool for 15 minutes. Serve.